Sourdough is a culture of wild yeast and lactobactillae. Wild yeast takes longer to ferment and will produce a more sour and complex flavor, whereas commercial yeast rises quicker.
A friend gave me some sourdough starter and I've been using it for a few months. I used advice from this guide by Emilie Raffa at theclevercarrot.com. What's so compelling to me about sourdough is how you can train it to fit your schedule. If you like baking daily you may want to keep your starter room temperature, if you don't keep it in the fridge. I bake 2-3 times a week using the recipe in that guide for both bread or pizza dough. I usually take some starter for bread or biscuits, then weigh and feed the remaining starter at a ratio of 1:1:1. One part starter, one part flour, one part water. If I'll be baking more, I'll leave that out to warm up. If not, I'll put it in the fridge to slowly rise and take it out later to warm up and become active before use. Sometimes I'll bake a bunch to use up an abundance of starter, sometimes I'll feed it twice because it's low. Once you get an understanding of how you want to use your starter, you can intuitively adjust to both save time and maintain a healthy starter.